The proposed project represents an extension of continuing studies on radiation cataractogenesis, the clinical aspects of which have been a major focus of investigation in this laboratory for the past 2 decades. In an effort to elucidate the mechanism of radiation cataractogenesis we plan, over the next 5 years, to concentrate on 1) the possible contribution of radiation-induced inflammation on the overall cataractogenic response; and 2) the nature of meridonal row disorganization and its role in radiation cataractogenesis. 1) To determine what contribution, if any, inflammation may make to radiation cataract development, comparative slit-lamp biomicroscopic studies will be undertaken on cataractogenesis following inflammatory and non-inflammatory doses of X-rays administered to the rat eye. We will also attempt to alter the time course or severity of cataract development in the rat eye following non-inflammatory doses of X-rays in conjunction with endotoxin induced uveitis. An effort will also be made to produce radiation cataracts in the rabbit eye in the absence of an inflammatory response. 2) Cellular studies on possible changes in morphology and ultrastructure as well as macromolecular syntheses in the meridional rows will also be undertaken. Because the epithelial cells are intimately involved in radiation cataractogenesis we will examine the changes in the cell kinetics and macromolecular syntheses of those cells to determine if they are primarily damaged before reaching the meridonal rows or subject to errant morphogenic cues subsequent to their entry into that region. The cellular studies will be pursued following inflammatory, as well as, non-inflammatory cataractogenic doses of X-rays. In addition, the changes will be compared with those brought about by endotoxin induced intraocular inflammation.